This invention relates in general to communication systems and more specifically to an apparatus and method for estimating jitter invoice packets received over a network running the Internet Protocol (IP).
The Internet Engineering Task Force (IETF) has developed a standard for transmission of voice traffic over packet data networks running the Internet Protocol. This Real Time Protocol (RTP) is defined in RFC 1889. The Real Time Protocol requires an estimate of the jitter in the arrival time of each received voice packet (referred to herein as the interarrival jitter). A value for the interarrival jitter is required for each voice stream, and the calculation is required to be performed every time that a voice packet is received.
Traditionally, the value for interarrival jitter has been calculated using software algorithms. However, this calculation represents significant processing overhead when many separate voice streams are being received simultaneously.
According to the present invention, a system is provided for estimating interarrival jitter in real time, using hardware elements. The apparatus of the present invention is capable of processing orders of magnitude more packetized voice streams than prior art software implementations. According to a preferred embodiment of the invention, a plurality of registers and arithmetic units are used to process packet spacing values to generate an estimate of the packet interarrival jitter. The hardware elements are controlled by a state machine whose operation is initiated by the reception of a packet of voice data.